Loose 'clean out' screw on GPR rifle

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Bledfor Days

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I recently aquired a used GPR .54 rifle. It has quite a bit of surface rust in the bore which was bothersome but I managed to clean it up. I was cleaning the nipple hole and noticed the clean out screw was in further than my other Lyman rifle. I was quite surprised that it screws in and out with very little difficulty. This is odd considering every thing else was crusty.
I'm in the 'don't screw with the screw' camp and am thinking about JB welding it in place. Shouldn't there be a stop that keeps it from screwing all the way into the drum? I'm worried it could be compromised and unsafe.
 

lyman54

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Had the same rifle and same problem. I drilled and tapped for a larger screw. You could try what rusty suggested or yeah, some JB Weld over the screw would do it also.
 

SDSmlf

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I would definitely not recommend JB weld or plumber’s tape for loose fitting ‘clean out’ screw. A loose fit between a male and female thread will not have the holding power of one that has the proper fit. Can’t tell you how much holding strength you have lost because we don’t know the actual sizes.

This is a high pressure area just off the main chamber. You do not want the screw’s holding power compromised. Have heard accounts of clean out screws coming out at high velocity when the gun is fired. Seems to get lefties in the arm when shooting right handed guns, not to mention the danger to those to your right (assuming a right hand gun).

Suggest you go up to the next largest fine pitch thread (metric or inch) and redrill and tap for a screw of that size. Recommend going to a thread size that uses a tap drill larger than the current set screw.
 

Zonie

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Bledfor Days:

Your problem is pretty typical with the "clean out screws". The hole is tapped deeper than the point that would prevent the screw from interfering with the nipple and if you don't want to clean the gun with the screw removed, I see nothing wrong with using some locking compound to lock it in place.

JB Weld is pretty tough stuff and it takes a lot of heat to make it break loose so, based on the idea that you may someday want to be able to remove the screw I recommend using the low strength BLUE Loc-Tight thread locking compound.

This stuff comes in a small bottle and it doesn't cost a lot. It also needs the threads on the screw and in the hole to be oil free and clean.
To use it, clean the hole and screw with alcohol. Place a small drop on the screw threads and while looking down the nipple hole, screw the screw in just to the place where you can start to see the end of the screw. Then let it sit for a few hours.

This in no way will reduce the strength of the screw threads and it will very likely seal them and prevent hot powder gas from blowing thru the threads when the gun fires.
 

SDSmlf

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Bledfor Days:

Your problem is pretty typical with the "clean out screws". The hole is tapped deeper than the point that would prevent the screw from interfering with the nipple and if you don't want to clean the gun with the screw removed, I see nothing wrong with using some locking compound to lock it in place.

JB Weld is pretty tough stuff and it takes a lot of heat to make it break loose so, based on the idea that you may someday want to be able to remove the screw I recommend using the low strength BLUE Loc-Tight thread locking compound.

This stuff comes in a small bottle and it doesn't cost a lot. It also needs the threads on the screw and in the hole to be oil free and clean.
To use it, clean the hole and screw with alcohol. Place a small drop on the screw threads and while looking down the nipple hole, screw the screw in just to the place where you can start to see the end of the screw. Then let it sit for a few hours.

This in no way will reduce the strength of the screw threads and it will very likely seal them and prevent hot powder gas from blowing thru the threads when the gun fires.
Clean out screw going deeper is different that a loose screw. Believe Green Mountain had an issue with deep seated or long clean out screws interferring with nipples at one point. Blocked flame channel issue. Loose fitting clean out screws means excessive clearance between the screw and the tapped hole. Depends on what the OP has. Spent 25 years designing and building high pressure valves. Loose threads are not something to be trifled with.
 

Bledfor Days

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Thank you for all the replies. I think I'll get it drilled and tapped for the next larger size screw. I shoot with a group and just can't risk someone else's safety. I guess I could be the last shooter on the right in the meantime ;^)
 

Bledfor Days

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Update: Good news. I have a GPR Hunter barrel that's never been fired and thought I'd try and see if it's plug/screw would fit better. The Hunters plug has an allen head on it and came out fairly easy. It went into the rusty barrel much firmer and stopped well outside the nipple hole.
So it was just the screw that was hooped. I got out to the range today and for a once rusty, neglected rifle, it is deadly accurate.
Thanks for all the replies. I forgot about the other barrel (spare parts.)20190524_131736.jpg
 
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